How do you use sprites in ui.newButton?

Solar2D General Questions/Discussion
#1 
local levelThumbSprites = spriteGrabber.grabSheet("sprite\_levelThumbs");  
local thumbSprite = levelThumbSprites:grabSprite("level1", true)  
--or whatever way you choose to obtain a sprite  
  
 local levelThumbBtn = ui.newButton{  
 defaultSrc = thumbSprite,  
 defaultX = 50,  
 defaultY = 32,  
 overSrc = thumbSprite,  
 overX = 50,  
 overY = 32,  
 overScale = 1.05,  
 onEvent = levelSelected,  
 }  
  
levelThumbBtn.x = 0;  
levelThumbBtn.y = 0;  
myGroup:insert(levelThumbBtn);

The button is not displayed anywhere… [import]uid: 52127 topic_id: 13695 reply_id: 313695[/import]